A swivel joint for a construction machine is used to couple tubes for communication between hydraulic equipment disposed on the swing structure, such as a valve apparatus for control of travel motors, and hydraulic equipment mounted to the travel structure, such as the travel motors, in a relatively rotatable manner. The swivel joint comprises a body and a spindle rotatably inserted in the body. A plurality of circumferential grooves are formed in each of an inner circumferential surface of the body and an outer circumferential surface of the spindle, and a plurality of axial passages are formed inside the spindle. A plurality of tubes connected to the body and a plurality of tubes connected to the spindle are held in communicated state in corresponding relation through the circumferential grooves and the axial passages.
In general, there are two types of structures for the swivel joint. One structure is the type (spindle fixed type) in which the spindle is mounted to the travel structure (travel frame) and the body is mounted to be rotatable together with the swing structure (swing structure main frame). The other is the type (body fixed type) in which the body is mounted to the travel structure (travel frame) and the spindle is mounted to be rotatable together with the swing structure (swing structure main frame). The former (spindle fixed type) is disclosed in, e.g., JP,U 5-64243, and the latter (body fixed type) is disclosed in, e.g., JP,Y 7-26445 and JP,A 9-328778.                Patent Document 1: JP,U 5-64243        Patent Document 2: JP,Y 7-26445        Patent Document 3: JP,A 9-328778        